10 Best Tankless Hot Water Heaters 2025 in the United States

The Rinnai RX199iN is a powerful tankless water heater that stands out for its impressive flow rate of up to 11.1 gallons per minute, making it suitable for homes with multiple fixtures needing hot water simultaneously. It's designed to operate on either natural gas or propane, giving you flexibility depending on your fuel source. The energy efficiency is top-notch, boasting a UEF rating of .98, which means it uses energy very effectively, potentially saving you on utility bills.

The Rinnai RE140iP is a propane-fueled tankless water heater designed for indoor use that delivers up to 5.3 gallons per minute (GPM), which means it can supply hot water to about five fixtures at the same time. This flow rate generally fits medium-sized homes or households with moderate simultaneous hot water needs. It uses 140,000 BTU of power, which is strong enough to provide a good temperature rise even if your incoming water is cold, making it suitable for most climates when properly sized.

The Rinnai RE140iN Non-Condensing Natural Gas Tankless Water Heater is a compact and efficient option for providing continuous hot water in your home. With a flow rate of up to 5.3 gallons per minute, it can handle multiple fixtures simultaneously, making it suitable for medium to large households. The high energy efficiency ensures lower utility bills as it only heats water when necessary. Its natural gas fuel type is generally more cost-effective than electric models, although it requires a gas line for installation.